Multiple copy seven-segment impact printer

ABSTRACT

A seven-segment printer mechanism capable of producing multiple impressions by impact on a pressure sensitive stack of thin sheets of paper or the like is disclosed. The printer includes an array of seven electromagnetically actuated styli positioned above a flat platen which is moved under the styli in a direction parallel to its flat surface to distribute the indicia produced by actuation of the styli along the upper surfaces of an assembled pressure sensitive stack of sheets of paper or the like carried by the platen. Specific electrical and mechanical features of the array of styli, as well as of the platen and its control are disclosed. The electronic circuitry for operating the printer is described and a novel mechanism for moving an inked ribbon under the styli to produce an impression on the upper surface of the topmost sheet of the stack is disclosed.

United States Patent 1 Holman et a1.

[ 1 Dec. 2, 1975 [5 MULTIPLE COPY SEVEN SEGMENT IMPACT PRINTER [73] Assignee: Holman Industries, Inc., Oakdale,

Calif.

22 Filed: Nov. 13,1974

211 Appl. No.: 523,460

[52] US. Cl. 197/1 R; 197/1 R X 3,804,224 4/1974 Barnaby ct a1 197/1 R Primary ExaminerWm. H. Grieb Attorney, Agent, or FirmPhillips, Moore,

Weissenberger Lempio & Strabala [57] ABSTRACT A seven-segment printer mechanism capable of producing multiple impressions by impact on a pressure sensitive stack of thin sheets of paper or the like is disclosed. The printer includes an array of seven electromagnetically actuated styli positioned above a flat platen which is moved under the styli in a direction parallel to its flat surface to distribute the indicia produced by actuation of the styli along the upper surfaces of an assembled pressure sensitive stack of sheets of paper or the like carried by the platen. Specific electrical and mechanical features of the array of styli, as well as of the platen and its control are disclosed. The electronic circuitry for operating the printer is described and a novel mechanism for moving an inked ribbon under the styli to produce an impression on the upper surface of the topmost sheet of the stack is disclosed.

14 Claims, 18 Drawing Figures us. Patent 1360.2, 19;,- sheetlofs 3,923,135

U.S. P1t6nt De c. 2, 1975 Sheet 3 of5 3,923,135

FIG .13

65 FIG 16 U.S. Patent Dec. 2, 1975 Sheet 4 of5 3,923,135

I? '2' PRINT SELECT AND MOTOR LOGIC PRINT SEQUENCE 3 CHANNEL BDC SEVEN SEGMENT DECODER UNITS TENS HUNDREDS 3 CHANNEL BDC THOUSANDS SEvEN SEGMENT DECODER TEN THOUSANDS T FIG -17 US. Patent Dec. 2, 1975 Sheet 5 of5 3,923,135

MOTOR AND TICKET CLAMP DRIVER SEVEN I SEGMENT DRIVER POWER SUPPLY Z A T FIG..17B

MULTIPLE COPY SEVEN-SEGMENT IMPACT PRINTER BACKGROUND OF THE INVENTION This invention relates to a printer and more specifically to a seven-segment printer capable of rapidly and simultaneously producing a large number of copies of each seven-segment character of a plurality of characters, such as numerical integers, by selective impact of styli of an array of seven styli each adapted to provide a different segment of the seven segment font of characters upon a pressure sensitive stack of a plurality of sheets of paper or the like.

The use of seven appropriately spaced straight line segments to display or record numerical characters or integers is well known in the art. It will be understood that any numerical integer from 0. through 9 as well as certain letters of the alphabet can be displayed or printed in a form readily intelligible to a human operator through the use of selected ones of seven appropriately spaced straight line segments.

It will also be understood that devices for displaying or recording numerical values based on the formation of numerical integers from seven appropriately spaced straight line segments are particularly useful as adjuncts to digital electronic devices which are capable of generating digital numerical outputs at an extremely high rate of speed since such display and recording devices enable the formation of the numerical integers at a high rate of speed with a minimum number of moving parts. Thus, the application of electrical or electrostatic forces to a sheet-like recording medium by means of electrodes in the form of seven appropriately spaced straight lines segments which may be selectively energized is proposed in U.S. Pat. Nos. 2,715,360 and 3,277,818, respectively.

However, such devices are inherently limited to use with a single sheet-like recording medium and it is substantially impossible to simultaneously produce a particular numerical integer or group of integers on multiple sheets of a recording medium through the use of electrical or electrostatic forces applied by a particular set of electrodes. It will be understood that, in certain applications, it is essential that a number of simultaneous recordings on multiple sheets of a recording medium be made of the voutput of a digital electronic device at a particular point in time.

It is an object of this invention to provide a printing device capable of making simultaneous copies of a particular integer or character on multiple sheets of a recording medium through the use of a single set of seven-segment printing elements, which device is capable of use with digital electronic devices to record the outputs thereof.

U.S. Pat. No. 3,1 12,693 discloses the use of appropriately spaced straight line segment type elements, each made of electrostrictive material, which are subjected to an electric field to cause them to distort or expand into contact with the recording medium. However, the amount of such distortion is small even where relatively large amounts of electrical power are utilized in the LII electric fields thus limiting the number of multiple recording sheets upon which simultaneous copies can be made even where a striking means is used to force the type elements against the recording medium. It will be understood that the application of sufficient force to cause the protruding type elements to make an impression on multiple sheets of recording medium will tend to bring the non-protruding type elements into contact with the recording medium thus making the amount of distortion or expansion of such elements with respect to each other the controlling factor in the number of sheets of recording medium that can be used.

Similarly, U.S. Pat. No. 3,367,469 discloses a printing head made up of seven straight line type elements slidably disposed in a framework and appropriately spaced from each other to enable the printing of sevensegment integers by selective retraction of certain of such elements with respect to the others. Such retraction is accomplished by means of an electromagnet system and the actual printing is subsequently accomplished by moving the platen which carries the recording medium into compressive contact with the unretracted type elements.

Thus, the device proposed in U.S. Pat. No. 3,367,469 is inherently slow in its operation since two steps are required for the printing of each integer. In other words, all of the type elements must first be positioned with respect to each other and then the platen must be moved to bring the type elements into compressive contact with the recording medium.

It is a further object of this invention to provide a mechanical printing device capable of rapidly making simultaneous copies of a particular integer or character representative of a given output of a digital electronic device on multiple sheets of a recording medium.

SUMMARY OF THE INVENTION According to this invention an impact printer is provided which includes a flat base plate having a plurality of solenoids mounted thereon in a preferably circular array with their axes parallel to each other and normal to the major surfaces of the base plate; a plurality of generally U-shaped stylus members each comprising a pair of parallel legs joined by a bight portion, one of such legs including a solenoid armature and the other of such legs terminating at its free end in an impact printing surface; and a platen member mounted on one side of the circular array of solenoids having a flat surface facing the base plate, the plane of such flat surface being parallel to the major surfaces of the base plate and the platen member being mounted for reciprocal movement in the plane of such flat surface. The base plate member has a plurality of apertures therethrough spaced from each other about the center of the circular array of solenoids and each of the plurality of U-shape stylus members has the one leg thereof including the solenoid armature operatively associated with a different one of the plurality of solenoids and the free end of the other leg thereof received through a different one of the apertures through the base plate. Thus, energization of each of the plurality of solenoids will accelerate the impact printing surface on the free end of the other leg of a different one of the U-shape stylus members toward contact with the flat surface of the platen member.

The impact printer preferably includes electronic means for converting a digital word to a plurality of electrical pulses for selected energization of the solenoids to produce numerical integers or other characters corresponding to the digital word. Motive means are included in the printer for moving the platen for a given distance from a given starting point and then returning the platen to such starting point. The impact printer may also include a means for moving an inked ribbon between the impact printing surfaces of the stylus members and the platen.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects and features of the subject invention will be more clearly apparent from the following detailed description of a preferred embodiment thereof when read in conjunction with the attached drawings wherein:

FIG. 1 is a perspective of one embodiment of the impact printer according to the teachings of this invention;

FIG. 2 is a top view of the embodiment of this invention shown in FIG. 1 with the top cover thereof removed to show the internal structure thereof;

FIG. 3 is a bottom view of the embodiment of this invention shown in FIG. 1 with the bottom cover removed to show the internal structure thereof;

FIG. 4 is a side view of the embodiment of this invention shown in FIG. 1 taken from the right side thereof with the top cover removed to show the internal structure thereof;

FIG. 5 is a perspective view of an assembled array of pressure sensitive sheets of paper or the like suitable for use with the embodiment of this invention shown in FIG. 1;

FIG. 6 is a perspective view of the printer head subassembly of the embodiment of this invention shown in FIG. 1;

FIG. 7 is a top view of the sub-assembly of FIG. 6;

FIG. 8 is an enlarged fragmentary bottom view of the printer head sub-assembly of FIGS. 6 and 7 showing the impact surfaces of the stylus members thereof;

FIG. 9 is an enlarged side view of a generally U- shaped stylus member of the sub-assembly of FIGS. 6 through 8;

FIG. 10 depicts a seven segment font of numerical integers which may be printed by the embodiment of this invention shown in FIG. 1 with the scale of such integers substantially equal to the scale of FIG. 8;

FIG. 11 depicts the alphabetical characters which may be printed by the embodiment of this invention shown in FIG. 1 with the scale of FIG. 11 being substantially the same as the scale of FIG. 10;

FIG. 12 is an enlarged fragmentary cross-sectional view of the platen of the embodiment of this invention shown in FIG. 1 with the free ends of a plurality of stylus members bearing the impact printing surfaces thereof shown in full in operative relation to the platen member in substantially the same scale as the scales of FIGS. 8 through 11;

FIG. 13 is a perspective view of the bottom of a further embodiment of an impact printer in accordance with the teaching of this invention with the bottom cover thereof removed to show the internal structure;

FIG. 14 is an exploded fragmentary view of the electrical and mechanical control elements which are included in the means for moving the platen of the embodiment of this invention shown in FIG. 13;

FIG. 15 is an enlarged top view of a means for moving an inked ribbon between the impact printing surfaces of the stylus members and the platen according to the teaching of this invention;

FIG. 16 is a front view of the means for moving an inked ribbon as shown in FIG. 15 mounted on a printer head as shown in FIG. 7; and 7 FIGS. 17A and 17B together show a wiring diagram for the electrical and electronic circuitry of the embodiment of this invention shown in FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring to FIG. 1, an embodiment 10 of the impact printer according to the teaching of this invention is shown. The embodiment 10 includes a frame 11 which carries a platen 12 having a flat upper surface. The platen 12 is mounted on the frame 11 for reciprocal movement as indicated by the double-headed arrow 13. The upper surface of the platen 12 may be provided with a resilient impact receiving strip 14 located on the platen to be moved under the impact printing surfaces of the stylus members upon reciprocation of the platen 12 as will be more fully described hereinafter.

The front panel 15 of the embodiment 10 may include appropriate indicia such as arrow 16 to indicate the location of the array of impact printing stylus members together with an appropriate control such as the start button 17 for initiating the operation of the device.

According to the embodiment 10 of this invention, a control means indicated at 18 is included for controlling the length of the reciprocating motion of the platen 12 indicated by the double-headed arrow 13. An appropriate top cover 19 is provided to protect the internal structure of the embodiment 10.

It will be understood that the embodiment 10 of this invention is connected to an appropriate source of electrical power (not shown). It will also be understood that the embodiment 10 of this invention includes an appropriate input means such as the socket means 20 (see FIG. 2) for coupling to the output of an electronic instrument or other device (not shown) capable of producing an electrical signal in the form of a digital word representative of a numerical integer or alphabetical character to be printed by the embodiment 10. For example, the electronic instrument or device (not shown) may be an electronic scales which produces a binary coded decimal digital word representative of the weight of an object or thing placed thereon.

Thus, referring to FIG. 2, which isa top view of the embodiment 10 of FIG. 1 with the top cover 19 removed to show the internal structure, an appropriate power supply is indicated at 21 for providing the necessary electrical and electronic power for operation of the embodiment 10. The embodiment 10 also includes appropriate electronic circuitry which may include a plurality of integrated circuit boards 22, for example, for converting the digital word applied to the embodiment 10 through the socket 20 into appropriate electrical pulses for the operation of the impact printer head, as will be more fully described hereinafter. Finally, as shown in FIG. 2, a pair of reels 23 and 24, together with other appropriate mechanisms as will be more fully described hereinafter, may be provided for moving an inked ribbon 25 between the impact printing surfaces of the stylus members of the printer head and the impact receiving surface 14 of the platen 12.

Referring to FIG. 3, a bottom view of the embodiment 10 is shown. The bottom cover (not shown) has been removed to expose the internal mechanism for reciprocation of the platen 12 in the direction indicated by the double-headed arrow 13. Such mechanism may include an electric motor 30 mechanically coupled to a chain 31 by an appropriate sprocket, for example. The chain 31 is in turn mechanically fixed to the platen 12 so that rotation of the motor in one direction will move the platen into the embodiment 10, whereas rotation of the motor 30 in the opposite direction will tend to move the platen out of the embodiment 10. As shown in FIG. 3, the platen 12 is mounted on the frame 11 by means of an appropriate guide rod 32 and guide member 33. The control means indicated at 18 for adjusting the length of the movement of the platen 12 into and out of the device 10 includes an electrode block 35 mounted on the frame 11 by means of a mounting rod 36 to enable the adjustment of its position along such mounting rod'36. The control means also includes an electrical contact means 37 carried by the platen l2 and adapted to cooperate with the electrode block 35 to control the length of the movement of the platen 12 as will be more fully discussed hereinafter.

Referring to FIG. 4, a side view of the embodiment 10 of FIG. 1 is shown with the top cover 19 removed. As shown in FIG. 4, an appropriate On Off switch 40 and fuse 41 are provided on the back panel 42 of the embodiment 10 and are electrically interposed between the input (not shown) for electrical power and the power supply 21. As also shown in FIG. 4, the impact printing head (to be more fully described hereinafter) is shown generally at 45, mounted above the platen 12 and carrying the reel 23 of the mechanism for moving an inked ribbon under the impact printing surfaces of the stylus members of the impact printing head. It will be understood that the impact printing head is spaced above the top surface of the platen 12 by a sufficient distance to allow a pressure sensitive assembly of a plurality of sheets of paper or the like to be carried by the platen under the printing head. Referring to FIG. 5, a somewhat enlarged perspective view of an appropriate pressure sensitive assembly of a plurality of sheets of paper or the like is shown. Such assembly may comprise a plurality of weight recording tickets 51 made of fairly thin paper and bound at one of their ends 52, one above the other, on an appropriate fairly stiff backing member 53 of light cardboard or the like with a plurality of slips of carbon paper or the like (not shown) therebetween.

It will be understood that in many instances it is necessary to make multiple simultaneous recordings of the reading of an instrument. For example, where the cargo of a truck is to be weighed for the purpose of determining the value thereof, it is imperative that a plurality of simultaneous copies of the weight be made, each of which copies will be retained by a different person, in order to avoid the possibility of error or even fraud. Where the scales used in weighing the truck cargo is an electronic instrument which produces a digital word or a binary coded digital word representative of the weight of the truck, it has not heretofore been possible to make multiple simultaneous recordings of such digital word for the reasons set forth hereinabove.

According to this invention, the pressure sensitive assembly 50 of FIG. 5 would be placed on the platen 12 of the embodiment 10 with the backing member 53 in contact with the top of the platen 12. The assembly 50 would be oriented over the impact receiving strip 14 of the platen l2 and the control means 18 adjusted to provide a recording on the assembly 50 in the desired location. The Start button 17 would then be pressed to activate the device causing the platen 12 to be moved into the machine under the printing head and simultaneously causing the device to produce a series of sevensegment numerical integers representative of the digital word provided to the device at the input socket 20. According to the teaching of this invention the printing head 45 is capable of producing clear copies of such numerical integers on more than six assembled sheets of paper or the like, as will be more fully discussed hereinafter. When the printing operation is complete, the platen 12 will return to its position projecting from the device 10 to enable the assembly 50 to be removed therefrom. It will be understood that the operation may be repeated with a given assembly 50 to provide a record of the weight of an empty truck and, subsequently, a record of the weight of the loaded truck in order to provide multiple copies made simultaneously of both weights to thereby avoid any possibility of error or fraud.

Referring to FIG. 6, an enlarged perspective view of the impact printing head 45 in accordance with the teaching of this invention is shown. The impact printing head comprises a plurality of solenoids 61 mounted in circular array between a supporting base plate 62 and a guiding base plate 63, the axes of the solenoids 61 being parallel to each other and normal to the major surfaces of the base plates 62 and 63. The supporting base plate 62 is provided with mounting flanges 64 at its ends and stiffening ribs 65 along its sides. It will be understood that the solenoids 61 are rigidly mounted on the supporting base plate 62 and the guiding base plate 63 is rigidly mounted on the solenoids 61, thus providing a mechanically rigid unitary structure.

As best shown in FIG. 7, a plurality of apertures 66 are provided through the supporting base plate 62 in circular array with each aperture 66 being aligned with the axis of a different one of the plurality of solenoids 61. As also best shown in FIG. 7, a further aperture 67 is provided through the supporting base plate 62 at the center of the circular array of solenoids 61 and apertures 66.

The guiding base plate 63 is also provided with an aperture therethrough at the center of the circular array of solenoids 61. Thus, referring to FIG. 8, an enlarged fragmentary view of the central portion of the guiding base plate 63 is shown having an aperture 68 therethrough corresponding to the aperture 67 through the supporting base plate 62. As best shown in FIG. 8, a circular insert member 69 is received in the aperture 68 through the guiding base plate 63. An identical insert member 69 is received in the aperture 67 through the base plate 62. Both of such insert members 69 are provided with a plurality of small apertures 70 therethrough which apertures 70 are arranged in a specific pattern as will be more fully disclosed hereinbelow.

Referring again to FIGS. 6 and 7, a plurality of impact printing stylus members 71 each associated with a different one of the solenoids 61 and apertures 66 are mounted on the upper surface of the supporting base plate 62 by means of helical compression springs 72. A representative impact printing stylus member 71 is shown in FIG. 9 in enlarged side elevation.

As shown in FIG. 9, each impact printing stylus member 71 is generally U-shaped with one leg 73 and the bight portion 74 of the U-shape being formed by a stiff wire or rod-like member bent to form substantially a right angle. The other leg 76 of the U-shape comprises a fairly heavy cylindrical plug or armature of magnetic material dimensioned to be received through the apertures 66 and into the solenoids 61. It will be understood that the helical compression springs 72 surround the leg 76 of the U-shaped stylus member 71 and bear against the bight portion 74 thereof to bias the solenoid armature provided by the leg 76 outwardly of the solenoids 61.

As shown in FIG. 9, the leg 73 of the U-shape stylus member 71 is substantially longer than the leg 76 thereof which provides the solenoid armature. Thus the leg 73 of each stylus member 71 is received through a different one of the plurality of apertures 70 through the insert members 69 received in the apertures 67 and 68 of the supporting base plate 62 and guiding base plate 63 respectively when such stylus member 71 is supported solely by the helical compression springs 72. It will be understood that upon energization of the solenoid 61 associated with a particular stylus member 71, the leg 76 of the stylus member 71 will be pulled downwardly into the solenoid 61 against the force of the compression spring 72 thus tending to cause the free end of the leg 73 of such stylus member 71 to project from the bottom surface of the guide base plate 63 through the aperture 70 in the insert member 69 associated therewith.

As best shown in FIGS. 8 and 9, the free end of the leg 73 of each stylus member 71 is beveled to provide sloping surfaces 77 tapering toward each other to form an impact printing surface 78 in the form of a ridge or straight line segment.

Considering now FIG. 8 in conjunction with FIGS. 10 and 11, it will be understood that the apertures 70 in the insert members 69 and the positioning of the straight line segment impact printing surface 78 at the free end of the leg 73 of each impact printing stylus member 71 are selected to enable the formation of seven-segment numerical integers and certain characters of the alphabet through selective actuation of various ones of the stylus members. Thus, in the embodiments of this invention specifically disclosed herein, seven stylus members 71 together with the seven associated solenoids 61 (with the understanding that an eighth solenoid and stylus member may be added to the array in order to provide a decimal point if desired) are included in the impact printing head 45.

Referring to FIG. 12, an enlarged fragmentary crosssectional view of the platen 12 according to the teaching of this invention is shown with the impact printing surfaces 78 of certain of the stylus members 71 shown in close spaced relation thereto. From FIG. 12 it will be understood that the energization of the solenoids 61 will accelerate the impact printing surfaces 78 of the stylus members 71 toward the impact receiving surface 14 of the platen 12. Thus, a pressure sensitive medium placed on the platen 12 and interposed between the impact receiving surface 14 thereof and the stylus membets 7] can be marked as desired by selective energization of the solenoids 61. As suggested in FIG. 12, a group of solenoids may be simultaneously energized to accelerate a selected group of stylus members toward the platen 12. Since each of the stylus members 71 is individually actuated, the only limitation as to the number of copies which may be simultaneously made of the mark produced by a stylus member will be the force which can be imparted to the stylus members 71 by the electromagnetic field of the solenoid 61 and the inertia of the stylus member 71. We have found that it is possible to produce as many as ten or twelve clear copies of a particular numerical integer simultaneously using the impact printer head according to the teaching of this invention as described hereinabove.

It will be understood that the proper spacing between the various straight line segments of the seven-segment numerical integers or alphabetical characters is important to their readability. Such spacing is primarily determined by the relative spacing of the stylus members 71 themselves. However, such spacing can be modified by appropriate actuation of selected ones of the stylus members with relation to the movement of the platen 12. It will be understood that the platen 12 is moved continuously under the stylus members 71 thus enabling spacing of the straight line segments with respect to each other as well as spacing of the numerical integers or alphabetical characters formed of the straight line segments. Thus, as indicated in FIG. 12, the platen member reciprocates as indicated by the doubleheaded arrow 13 under the stylus members 71. By actuating the solenoids associated with the stylus members 71 in appropriate timed relation with respect to each other and with respect to the movement of the platen 12 the desired spacing of the straight line segments and of the integers and characters formed thereby may be obtained along the direction of travel of the platen 12.

It will be understood that the length of travel of the platen 12 will determine the number of integers or characters that may be included in a particular numerical quantity or word to be printed by the device 10 according to the teaching of this invention. Thus, in the particular embodiment of this invention shown in the drawing, the dimensions of the integers or characters printed by the impact printing head as determined by the relative spacing of the array of stylus members from each other and the total available length of travel of the platen 12 is such that a series of about 50 integers or characters could be printed in a single line. In other words, if a continuous series of integers or characters were printed in sequence by the impact printer head as the platen 12 moved throughout the entire length of travel of which it is capable either into or out of the device 10, a line of some 50 integers or characters would be produced. It will be understood that such line will be located along the impact receiving surface 14 of the platen (see FIGS. 1 and 2) and that by properly locating the pressure sensitive assembly 50 (See FIG. 5) with respect to such impact receiving surface 14 as by orienting the pressure sensitive assembly 50 with respect to the indicia 16 on the front panel 15 of the device 10 (see FIG. 1), any selected location of such line on the pressure sensitive assembly 50 may be obtained.

However, where a numerical quantity having less than fifty integers or a word having less than 50 characters is to be printed by the device 10, it becomes neces sary to provide an appropriate means for locating such numerical quantity or word at a desired location along the line of travel of the platen 12. Furthermore, it would be undesirable for the platen 12 to travel through the full available length of travel of which it is capable when such travel need only be sufficient for the printing of a few integers or characters. For example, the embodiment 10 of this invention shown in the drawing is specifically adapted to print numerical quantities consisting of six integers. Thus, the device 10 is coupled to an electronic scales for weighing trucks and the like, which scales produces a binary coded signal representing the weight imposed thereon which the device l converts to a numerical quantity in six integers. The electronic circuitry of the device is adapted to cause the platen 12 to move inwardly thereof a distance sufficient for the printing of six integers and then reverse the direction of travel tomove outwardly thereof to its starting point. Furthermore, according to the teaching of this invention the device 10 is provided with a control means 18 which enables the six integers to be placed at any preselected point along the line of some 50 integer or character locations which the device 10 is capable of providing.

Referring to FIGS. 3, 13 and 14, it will be seen that the mechanical elements of the control means 18 comprise the electrode block 35 mounted on the guide rod 36 for sliding adjustment along the available length of travel of the platen 12 and the electrical contact means 37 which is mounted on and carried by the platen 12.

Referring to FIG. 14, it will be seen that the electrical contact means 37 includes four flexible contact fingers 81, 82, 83, 84 mounted at one of their ends on an insulating block 85 together with one end of each of four separate electrical conductors 86, 87, 88 and 89 for making separate electrical connections to such fingers. The other ends of such fingers 81-84 are adapted to compressively contact the adjacent surface of the electrode block 35. The electrode block 35 is made of insulating material but the surface thereof which is contacted by the contact fingers 81-84 is provided with an electrically conductive coating or electrode 90 having the pattern or conformation shown in FIG. 14. Thus, the pattern of the electrode 90 includes a first area or portion 91 adapted to be contacted by the contact finger 81 only, which area or portion 91 extends the full length of the electrode block35 in a direction parallel to the guide rod 36. The pattern of the electrode 90 includes a second area or portion 92 adapted to be contacted only by the contact finger 82 of the electrical contact means 37 which area 92 extends less than half way along the surface of the block 35 from one end thereof. A third area or portion 93 of the electrode 90 is adapted to be contacted only by the contact finger 83 of the electrical contact means 37 and is located at the center of the surface of the block 35 along the length thereof parallel with the guide rod 36. Finally, a fourth area or portion 94 of the electrode 90 is adapted to be contacted only by the contact finger 84 and extends less than half way alongthe block 35 parallel to the guide rod 36 from the other end of such block 35.

As shown in FIG. 14, the ends of the area or portion 93 of the electrode 90 in the direction of the guide rod 36 correspond to the adjacent ends of the areas 92 and 94. Thus it will be seen that so long as the contact fingers 8l-84 are in contact with the surface of the block 35, two and only two of such contact fingers will make electrical contact with the electrode 90. The contact finger 81 will, of course, always be in electrical contact with the area 91 of the electrode 90. However, the areas 92, 93 and 94 are so dimensioned and spaced with respect to each other that relative movement between the block 35 and the electrical contact means 37 in a direction parallel to the axis of the guide rod 36 will resultin only one of the contact fingers 82, 83 and 84 being in contact with the corresponding area 92, 93, 94 of the electrode 90.

As will be more fully described hereinafter, the electrical connectors 87, 88 and 89 connect the contact fingers 82, 83 and 84 into appropriate circuitry whereby electrical contact between the finger 82 and the area 92 of electrode will cause the platen 12 to move in the direction parallel to the guide rod 36 toward the center of the block 35 to bring the finger 83 into contact with the area 93 whereas electrical contact between the finger 84 and the area 94 will cause the platen 12 to move in the direction parallel to the guide rod 36 toward the center of the block 35 to bring the contact finger 83 into contact with the area 93. It will be understood that the connector 86 is connected to appropriate circuitry to apply a desired potential to the contact finger 81 which in turn applies such potential to the electrode 90 so long as the contact fingers 81-84 of the electrical contact means 37 are in contact with the surface of the block 35. Such potential is in turn applied to one only of the contact fingers 82, 83, 84 depending on the relative position of the block 35 and the electrical contact means 37. Thus, the application of such potential to the electrical connector 87 through contact of the finger 82 with the area 92 causes the platen to move in one direction, the application of such potential to the electrical connector 88 through contact of the finger 83 with the area 93 will stop the movement of the platen l2 applying an appropriate braking means to prevent over travel of the platen 12, as will be more fully described herinafter, and the application of the potential to the connector 89 through contact of the finger 84 with area 94 will cause the platen 12 to move in the opposite direction until the finger 83 is brought into contact with the area 93.

From the above it will be understood that movement of the block 35 in either direction along the guide rod 36 will automatically cause the platen 12 which carries the electrical connection means 37 to move in the same sense as the block 35 is moved until the finger 83 again contacts the area 93. From the above it will be seen that manual adjustment of the control means 18 will produce a rapid and convenient positioning of the platen 12 at a selected point in the reciprocating travel for which it is designed. As best shown in FIG. 1, the block 35 may be provided with an appropriate adjustment and indicator arm 95 extending to the exterior of the frame 11 for convenient manual manipulation. It will be understood that the guide rod 36 is provided with a plurality of notches along its length to cooperate with an appropriate ratchet means (not shown) in the block 35 to facilitate positioning of the block 35 along the guide rod 36. Similarly, an appropriate scale 96 or other indicia may be provided on the exterior of the frame 11 to cooperate with the indicator arm 95 and provide a visual indication of the location of the rest position of the platen 12 along the length of its reciprocating travel.

Referring again to FIGS. 3 and 13, it will be seen that a pair of solenoids 98 are mounted on the lower surface of the platen 12. Such solenoids 98 actuate a clamping means on the upper surface of the platen 12 to automatically grip and hold a pressure sensitive assembly such as that shown in the FIG. 5 during reciprocation of the platen 12 and operation of the impact printing head 45. As will be more fully discussed hereinafter, the electronic circuitry of the device 10 is designed to override the action of the control means 18 to cause the platen 12 to reciprocate through a selected portion of its available travel starting from the position established by the control means 18 and moving inwardly of the device a distance sufficient for the printing of a selected number of integers or characters and then returning to its starting position. Such action is initiated by pressing the start button 17 on the front panel 15 of the device 10.

In addition to initiating reciprocation of the platen 12 and the impact printing cycle, the manual operation of the start button 17 on the front panel 15 of the device 10 also actuates a mechanism for moving an inked ribbon between the impact printing head 45 and the upper surface of the pressure sensitive assembly 50 in order to enable the printing of indicia on such upper surface by the stylus members 71. Referring to FIG. 15, a top view of the mechanism 105 for such transport of an inked ribbon 25 is shown. The mechanism 105 includes a pair of reels including a supply reel 23 and a take-up reel 24 removably mounted on a support structure 109 by means of spindles 111 and 112, respectively.

Referring to FIG. 16, it will be seen that the mechanism 105 is mounted on top of the impact printer head 45 by means of the support structure 109. The mechanism 105 includes guide members 113 and 114 positioned on opposite sides of the circular array of solenoids 61 and impact stylus members 71. Thus, as the inked ribbon 25 is fed off of the supply reel 23, it is threaded through the first guide member 113 which is adapted to alter the direction of travel of the ribbon by ninety degrees (as best shown in FIG. 16) and then passes under the guide base plate 63 and across the aperture 68 therein. After passing across the aperture 68 in the guide base plate 63, the inked ribbon travels upwardly and is threaded through the guide member 114 where its original direction of travel is restored. From the guide member 114 the ribbon passes through a drive mechanism comprising a driven spindle 115 and a pair of slave spindles 116. From the driving mechanism it is threaded onto the take-up reel 24. The spindle 115 of the driving mechanism is driven by a constant speed motor 117 mounted on the under surface of the supporting structure 109 as indicated by the dotted lines in FIG. 16. An appropriate drive belt 118 interconnects the driven spindle 115 of the driving mechanism and the spindle 112 on which the take-up reel 24 is carried. The drive belt 118 is adapted to provide a slip clutch action to allow the spindle 112 and take-up reel 24 to rotate more slowly than the drive spindle 115.

From the above it will be understood that manual operation of the start print button 17 will cause the constant speed motor 117 to drive the spindle 115 thereby transporting a given length of inked ribbon 25 under the aperture 68 in the guide base plate 63 for receiving the impact of the stylus members and imparting the desired markings to the upper surface of a pressuresensitive assembly 50 placed on the platen 12. The belt 118 interconnecting the spindle 115 and the spindle 1 12 will cause the take-up reel 24 to rotate and thereby receive the length of ribbon transported through the action of the spindle 115 during the printed cycle of the device 10. At the end of each printing cycle, the constant speed motor 117 is deenergized until the beginning of the next printing cycle. An appropriate microswitch 120 having a sensor arm 121 projecting into operative relation with the take-up reel 24 is provided to activate an appropriate alarm when the quantity of inked ribbon received on the take-up reel 24 approaches the total quantity of inked ribbon originally provided on the supply reel 23, thereby enabling re placement of the ribbon before the supply thereof is completely exhausted.

FIGS. 17A and 17B together constitute a wiring diagram of the preferred embodiment 10 described hereinabove with certain of the elements thereof shown in block form and others shown schematically. The same reference numerals are used for the block or schematic representation of such elements as used therefor in drawings 1 through 16 in order to simplify direct correlation between various drawings. Thus, referring to FIG. 17A, the start print button 17 and the input socket or jack 20 are shown electrically connected to certain ones of the integrated printed circuit boards 22. Similarly, referring to FIG. 17B, the power supply 21 is shown in block form connected to a source of power through the on-off switch and fuse 41, the reversible motor 30 for driving the platen 12 is shown electrically connected to another one of the integrated printed circuit boards 22 and the solenoids 61 of the impact printing head are shown electrically connected to a further one of the integrated printed circuit boards 22. FIG. 178 also shows the clamping solenoids 98 for holding the pressure-sensitive assembly in place on the platen 12 and the constant speed motor 117 for driving the ribbon transport means connected to the same integrated circuit board 22 as the platen drive motor 30. Finally, FIG. 178 includes a schematic representation of the platen travel control means 18.

As represented schematically in FIG. 173, the electrode of the electrode block 35 is shown in sliding contact with contact finger 81. Contact finger 81 is shown separately from the electrical contact means 37 and the contact fingers 82, 83 and 84 of the electrical contact means 37 are represented as simple switch elements adapted to engage simple contacts on the electrode block 35. Electrical connector 86 is shown connecting contact finger 81 to an appropriate terminal A on the power supply 21 to provide the necessary electrical potential on the electrode 90 of the electrode block 35. It will be understood that only one of the contact fingers 82-84 of the electrical contace means 37 will be in contact with the electrode 90 of the electrode block 35 at any particular moment in time, as described hereinabove, and electrical connectors 87-89 are shown connecting such contact fingers to appropriate integrated circuit boards 22 of FIGS. 17A and 178.

It should be pointed out that a pair of limit switches 122 and 124 are shown connected in parallel with contact fingers 82 and 84 respectively of the platen travel control means 18. These limit switches 122 and 124 are not shown in drawings 1-16, but are mounted on the platen 12 and include an appropriate mechanical pressure-sensing switch element adapted to be actuated at opposite ends of the travel of the platen 12 and automatically reverse the direction of such travel. Similarly, an indicator light 130 (which may take the form of a light-emitting diode and is not otherwise shown in the drawings) is indicated on FIG. 17A as being connected to the microswitch shown on FIG. 17B and a power-on indicator 132 which also may take the form of a light-emitting diode is shown on FIG. 17A. It will be seen that one side of both light-emitting diodes and 132 is connected to ground. Similarly, the other side of the light-emitting diode is directly connected to a terminal Z of the power supply, whereas the other side of the light-emitting diode 130 is connected to the terminal Z of the power supply through the switch 120 which is adapted to sense the quantity of inked ribbon received on the take-up reel 24 of the ribbon transport mechanism.

The functions performed by the circuits of the various integrated circuit boards 22 are indicated by the legends included within the blocks therefor. Thus, the integrated circuit board 22 bearing the legend Print, Select and Motor Logic, includes appropriate circuitry for causing the platen to reciprocate through a given pre-selected length in response to the manual actuation of the start button 17. It will be seen that the platen control means 18 is also connected to this circuit board, as are the limit switches 122 and 124. Thus, it will be understood that the circuitry of this circuit board also provides appropriate logic to override the action of the platen control means 18 in response to actuation of the start button 17 and to cause the platen to be driven in a particular direction in the event that none of the contact fingers of the electrical contact means 37 are in contact with the electrode 90 of the electrode block 35. For example, if the electrode block 35 is moved out of contact with the electrical contact means 37 while the device is turned off, then when the device 10 is turned on, the platen will move in the selected direction until one of the microswitches 122, 124 is actuated to reverse the direction of travel thereof. The platen will then continue to move in the reverse direction until the contact finger 83 is again in Contact with the area 93 of the electrode 90 to stop the platen in the selected position as established by the electrode block 35. The printed circuit board 22 labelled Print Sequence which is interposed between the circuit board 22 labelled Print Select and Motor Logic and the two printed circuit boards 22 labelled Three Channel BCD To Seven-Segment Decoder is a simple circuit adapted to control the timing of the printing of the various seven-segment characters as generated from the binary coded decimal signal applied to the input socket 20 through the action of the two decoder circuits each of which is capable of producing three seven-segment characters.

Referring to FIG. 17B the integrated circuit board 22 labelled Motor and Ticket Clamp Driver includes the circuitry necessary to convert the control signals produced by the circuit board labelled Print Select and Motor Logic into the actual control voltages and currents to be applied to the motors and 117 and to the solenoids 98. Similarly, the integrated printed circuit board 22 labelled Seven-Segment Driver includes the circuitry necessary to convert the control signals from the two Decoder integrated circuit boards to the appropriate voltages and currents for operation of the solenoids 61 of the impact printer head. Finally, the power supply 21 may comprise an integrated circuit board including appropriate circuitry for providing the necessary direct current voltages for operation of the various elements of the device.

'It will be understood that circuits for providing the functions broadly described above may take a wide variety of forms. However, according to the teaching of this invention, the provision of such circuits on individual integrated printed circuit boards 22 as described hereinabove enables a device according to the teaching of this invention to be readily adapted for operation with a wide variety of input signals.

Thus. additional integers or characters may be printed in a given print cycle by simply substituting different printed circuit boards having the desired added circuitry for Print Select and Motor Logic, Print Sequence, and Seven-Segment Decoder printed circuit boards. It will be understood that such printed circuit boards are preferably of the plug-in type in order to facilitate the interchange thereof.

Similarly, provision for a decimal point in a particular group of integers or characters may be easily accomplished by adding a further solenoid 61 and stylus member 71 and by including appropriate circuitry for the control and driving thereof. Preferably, the circuitry for controlling or timing the decimal point with respect to the other integers would be included on the Print Select and Motor Logic circuit board and the circuitry for driving the decimal point solenoid and stylus would be included on the Motor and Clamp Driver circuit board. The impact printing surface of the decimal point stylus would, of course, have an appropriate shape other than a straight line segment in order to produce a recognizable decimal point in conjunction with the sevensegment numerical integer or characters printed by the device.

From the above detailed description of a preferred embodiment of this invention it will be seen that novel and highly versatile electromechanical mechanisms are provided for printing se ven-segment numerical integers and characters, for controlling reciprocating motion of a platen or the like, and for transporting an inked ribbon with respect to a printing head. The various mechanisms are particularly suited for use with electronic circuitry of the printed circuit type and the printing mechanism is particularly suited for the production of a multiple printed record of the binary output of electronic measuring devices.

It is believed that those skilled in the art will devise various embodiments of this invention for use in various systems making obvious alterations in the preferred embodiments described herein as required for particular systems. Thus, the basic mechanisms and combinations thereof with each other and with appropriate electronic circuitry for which protection is sought are set forth in the following claims.

What is claimed is:

1. An impact printer comprising:

a. a flat base plate having parallel major surfaces;

b. a plurality of solenoids having parallel axes mounted in an array on one major surface of said base plate with their axes normal thereto;

c. a plurality of generally U-shape stylus members each comprising a pair of parallel legs joined by a bight portion, one of said legs including a solenoid armature member and the other of said legs terminating at its free end in an impact printing surface; and

d. a platen member having a flat surface mounted on one side of said array of solenoids with said flat surface thereof facing said base plate member and the plane thereof parallel to said major surfaces of said base plate member, said platen member being mounted for reciprocal movement in said plane of said flat surface thereof;

e. said base plate member having a plurality of apertures therethrough spaced from each other about the center of said array of solenoids;

f. said plurality of generally U-shape stylus members each having said one of said legs thereof in operative relation to a different one of said plurality of solenoids and said other of said legs thereof received through a different one of said apertures through said base plate member; whereby upon energization of one of said plurality of solenoids, the impact printing surface on said free end of said other one of said legs of the associated one of said plurality of U-shape stylus members will be accelerated toward said flat surface of said platen.

2. An impact printer as claimed in claim 1 wherein said one of said legs of each of said plurality of generally U-shape stylus members is shorter than said other of said legs thereof.

3. An impact printer as claimed in claim 1 wherein said impact printing surface at said free end of said other of said legs of each of said plurality of generally U-shape stylus members comprises a straight line segment.

4. An impact printer as claimed in claim 3 wherein said plurality of apertures through said base plate member are spaced from each other and said straight line segment impact printing surfaces at said free ends of said other legs of said plurality of generally U-shape stylus members are oriented with respect to each other to enable printing of numerical integers by selective energization of two or more of said plurality of solenoids.

5. An impact printer as claimed in claim 4 including seven solenoids, seven generally U-shape stylus members, and seven apertures through said base plate with each straight line impact surface at the free end of said other leg of a stylus member and each aperture oriented with respect to the others thereof to print a particular straight line segment of a seven-segment numerical integer upon energization of the solenoid associated therewith, said seven solenoids being arranged in circular array.

6. An impact printer as claimed in claim 5 including electronic means for converting a digital word to a plurality of electrical pulses and for applying each of said pulses to a different appropriate one of said solenoids to thereby energize selected ones of said solenoids to cause selected ones of said stylus members to print the numerical integer corresponding to said digital word.

7. An impact printer as claimed in claim 6 wherein said digital word is a binary coded decimal signal produced by an electronic measuring instrument.

8. An impact printer as claimed in claim 6 wherein motive means are provided continuously moving said platen in one direction for a given length from a given starting position and thereafter automatically returning said platen to said given starting position, said electronic means including means for timing said pulses with respect to movement of said platen.

9. An impact printer as claimed in claim 8 wherein means are provided moving an inked ribbon between said impact surfaces of said plurality of stylus members and said platen during application of said pulses to said solenoids.

10. An impact printer as claimed in claim 8 wherein said motive means includes means for adjusting said given starting position of movement of said platen in said one direction substantially independently of the said given length of movement of said platen.

11. An impact printer as claimed in claim 8 wherein said electronic means for converting a digital word to a plurality of electrical pulses comprise first and second integrated printed circuit boards of the plug-in type connected in parallel to said electronic means for applying said pulses to said solenoids comprising a third integrated printed circuit board; said means for continuously moving said platen in one direction for a given length from a given starting position and thereafter automatically returning said platen to said given starting position comprises fourth and fifth integrated printed circuit boards of the plug-in type electrically connected in series between the power input to said printer and an electric driving motor mechanically coupled to said platen; and said means for timing said pulses with respect to movement of said platen comprises a sixth integrated printed circuit board of the plug-in type electrically interposed between said fourth integrated printed circuit board and said first and second integrated circuit boards in parallel.

12. An impact printing device comprising:

a. a frame;

b. an impact printing head mounted on said frame;

0. a platen member having a flat impact receiving surface mounted on said frame for movement along a given path with said flat surface thereof spaced a given distance from said impact printing head;

d. motive means mounted on said frame and connected to said platen member for moving said platen member in either direction along said given path; and

e. control means for positioning said platen member at a selected point along said given path, said con trol means including an electrode block mounted on said frame for adjustable movement along said path of movement of said platen and an electrical contact means mounted on said platen for movement therewith, said electrode block having a conductive surface and said electrical contact means including a plurality of contact fingers adapted to contact said conductive surface of said electrode block during a portion of said movement of said platen member along said path, said conductive surface of said electrode block having a given shape and said contact finger being oriented with respect to each other and with respect to said conductive surface such that not more than two of said contact fingers will contact said conductive surface at any point in the relative travel of said electrode block and said electrical contact means with respect to each other along said path.

13. An impact printing device as claimed in claim 12 wherein said electrical contact means includes four contact fingers, a first one of said contact fingers being electrically connected to a given source of electrical potential, a second one of said contact fingers being electrically connected to cause said motive means to move said platen member in one direction along said path upon application of said given potential thereto, a third one of said contact fingers being electrically connected to cause said motive means to move said platen member in the other direction along said path upon application of said given electrical potential thereto and the fourth one of said contact fingers being electrically connected to deactivate said motive means upon application of said given electrical potential thereto; said contact fingers being oriented with respect to each other and with respect to said conductive surface such that said first one of said contact fingers is always one of said not more than two of said contact fingers in contact with said conductive surface and, when said fourth contact finger is in contact with said conductive surface, relative movement of said electrode block and electrical contact means with respect to each other in one direction along said path will simultaneously remove said fourth contact finger from said contact and bring said first contact finger into contact with said conductive surface whereas relative movement of said electrode block and electrical contact means with respect to each other in the other direction along said path will simultaneously remove said fourth contact finger from said contact and bring said third contact finger into contact with said conductive surface.

14. An impact printing device comprising: a. a frame; b. an impact printing head mounted on said frame; 0. a platen member having a flat impact receiving surface mounted on said frame for movement along a given path with said first surface thereof spaced a given distance from said impact printing head; d. means for transporting an inked ribbon between said impact printing head and said impact receiving surface of said platen comprising a supply reel carried by a free turning spindle mounted on said impact printing head, a take-up reel carried by a free turning spindle mounted on said impact printing head, a driven spindle mounted on said impact printing head together with motive means for driving'said driven spindle, a free turning slave spindle mounted on said impact head and associated with said driven spindle to enable said driven spindle to drive said inked ribbon when said inked ribbon is threaded between said driven spindle and said slave spindle, guide means mounted on said printing head for guiding said inked ribbon from said supply reel between said impact printing head and said impact receiving surface of said platen to said driven spindle and slave spindle for threading therebetween prior to being received on said take-up reel, and a friction drive belt mechanically coupling said driven spindle to said free turning spindle carrying said take-up reel, said mechanical coupling provided by said driving belt being of sufficiently low friction to enable said free turning spindle carrying said take-up reel to be driven by said driven spindle at lower rotational speeds than the rotational speed at which said driven spindle is driven. 

1. An impact printer comprising: a. a flat base plate having parallel major surfaces; b. a plurality of solenoids having parallel axes mounted in an array on one major surface of said base plate with their axes normal thereto; c. a plurality of generally U-shape stylus members each comprising a pair of parallel legs joined by a bight portion, one of said legs including a solenoid armature member and the other of said legs terminating at its free end in an impact printing surface; and d. a platen member having a flat surface mounted on one side of said array of solenoids with said flat surface thereof facing said base plate member and the plane thereof parallel to said major surfaces of said base plate member, said platen member being mounted for reciprocal movement in said plane of said flat surface thereof; e. said base plate member having a plurality of apertures therethrough spaced from each other about the center of said array of solenoids; f. said plurality of generally U-shape stylus members each having said one of said legs thereof in operative relation to a different one of said plurality of solenoids and said other of said legs thereof received through a different one of said apertures through said base plate member; whereby upon energization of one of said plurality of solenoids, the impact printing surface on said free end of said other one of said legs of the associated one of said plurality of U-shape stylus members will be accelerated toward said flat surface of said platen.
 2. An impact printer as claimed in claim 1 wherein said one of said legs of each of said plurality of generally U-shape stylus members is shorter than said other of said legs thereof.
 3. An impact printer as claimed in claim 1 wherein said impact printing surface at said free end of said other of said legs of each of said plurality of generally U-shape stylus members comprises a straight line segment.
 4. An impact printer as claimed in claim 3 wherein said plurality of apertures through said base plate member are spaced from each other and said straight line segment impact printing surfaces at said free ends of said other legs of said plurality of generally U-shape stylus members are oriented with respect to each other to enable printing of numerical integers by selective energization of two or more of said plurality of solenoids.
 5. An impact printer as claimed in claim 4 including seven solenoids, seven generally U-shape stylus members, and seven apertures through said base plate with each straight line impact surface at the free end of said other leg of a stylus member and each aperture oriented with respect to the others thereof to print a particular straight line segment of a seven-segment numerical integer upon energization of the solenoid associated therewith, said seven solenoids being arranged in circular array.
 6. An impact printer as claimed in claim 5 including electronic means for converting a digital word to a plurality of electrical pulses and for applying each of said pulses to a different appropriate one of said solenoids to thereby energize selected ones of said solenoids to cause selected ones of said stylus members to print the numerical integer corresponding to said digital word.
 7. An impact printer as claimed in claim 6 wherein said digital word is a binary coded decimal signal produced by an electronic measuring instrument.
 8. An impact printer as claimed in claim 6 wherein motive means are provided continuously moving said platen in one direction for a given length from a given starting position and thereafter automatically returning said platen to said given starting position, said electronic means including means for timing said pulses with respect to movement of said platen.
 9. An impact printer as claimed in claim 8 wherein means are provided moving an inked ribbon between said impact surfaces of said plurality of stylus members and said platen during application of said pulses to said solenoids.
 10. An impact printer as claimed in claim 8 wherein said motive means includes means for adjusting said given starting position of movement of said platen in said one direction substantially independently of the said given length of movement of said platen.
 11. An impact printer as claimed in claim 8 wherein said electronic means for converting a digital word to a plurality of electrical pulses comprise first and second integrated printed circuit boards of the plug-in type connected in parallel to said electronic means for applying said pulses to said solenoids comprising a third integrated printed circuit board; said means for continuously moving said platen in one direction for a given length from a given starting position and thereafter automatically returning said platen to said given starting position comprises fourth and fifth integrated printed circuit boards of the plug-in type electrically connected in series between the power input to said printer and an electric driving motor mechanically coupled to said platen; and said means for timing said pulses with respect to movement of said platen comprises a sixth integrated printed circuit board of the plug-in type electrically interposed between said fourth integrated printed circuit board and said first and second integrated circuit boards in parallel.
 12. An impact printing device comprising: a. a frame; b. an impact printing head mounted on said frame; c. a platen member having a flat impact receiving surface mounted on said frame for movement along a given path with said flat surface thereof spaced a given distance from said impact printing head; d. motive means mounted on said frame and connected to said platen member for moving said platen member in either direction along said given path; and e. control means for positioning said platen member at a selected point along said given path, said control means including an electrode block mounted on said frame for adjustable movement along said path of movement of said platen and an electrical contact means mounted on said platen for movement therewith, said electrode block having a conductive surface and said electrical contact means including a plurality of contact fingers adapted to contact said conductive surface of said electrode block during a portion of said movement of said platen member along said path, said conductive surfaCe of said electrode block having a given shape and said contact finger being oriented with respect to each other and with respect to said conductive surface such that not more than two of said contact fingers will contact said conductive surface at any point in the relative travel of said electrode block and said electrical contact means with respect to each other along said path.
 13. An impact printing device as claimed in claim 12 wherein said electrical contact means includes four contact fingers, a first one of said contact fingers being electrically connected to a given source of electrical potential, a second one of said contact fingers being electrically connected to cause said motive means to move said platen member in one direction along said path upon application of said given potential thereto, a third one of said contact fingers being electrically connected to cause said motive means to move said platen member in the other direction along said path upon application of said given electrical potential thereto and the fourth one of said contact fingers being electrically connected to deactivate said motive means upon application of said given electrical potential thereto; said contact fingers being oriented with respect to each other and with respect to said conductive surface such that said first one of said contact fingers is always one of said not more than two of said contact fingers in contact with said conductive surface and, when said fourth contact finger is in contact with said conductive surface, relative movement of said electrode block and electrical contact means with respect to each other in one direction along said path will simultaneously remove said fourth contact finger from said contact and bring said first contact finger into contact with said conductive surface whereas relative movement of said electrode block and electrical contact means with respect to each other in the other direction along said path will simultaneously remove said fourth contact finger from said contact and bring said third contact finger into contact with said conductive surface.
 14. An impact printing device comprising: a. a frame; b. an impact printing head mounted on said frame; c. a platen member having a flat impact receiving surface mounted on said frame for movement along a given path with said first surface thereof spaced a given distance from said impact printing head; d. means for transporting an inked ribbon between said impact printing head and said impact receiving surface of said platen comprising a supply reel carried by a free turning spindle mounted on said impact printing head, a take-up reel carried by a free turning spindle mounted on said impact printing head, a driven spindle mounted on said impact printing head together with motive means for driving said driven spindle, a free turning slave spindle mounted on said impact head and associated with said driven spindle to enable said driven spindle to drive said inked ribbon when said inked ribbon is threaded between said driven spindle and said slave spindle, guide means mounted on said printing head for guiding said inked ribbon from said supply reel between said impact printing head and said impact receiving surface of said platen to said driven spindle and slave spindle for threading therebetween prior to being received on said take-up reel, and a friction drive belt mechanically coupling said driven spindle to said free turning spindle carrying said take-up reel, said mechanical coupling provided by said driving belt being of sufficiently low friction to enable said free turning spindle carrying said take-up reel to be driven by said driven spindle at lower rotational speeds than the rotational speed at which said driven spindle is driven. 